Apparatus and process for treatment of fibers

ABSTRACT

A process for treatment of fibers is disclosed. The treatment comprises simultaneously and continuously macerating the fibers and exposing the fibers to superheated steam, ammonia gas and ethylenediamine gas. The treatment is carried out in a chamber where the fibers are subjected to the mechanical rubbing and crushing action of a plurality of rotating pins against channels disposed on the chamber interior wall. The treatment results in improved fiber water holding capacity and improved conversion efficiency in the production of biofuels from the treated fibers.

RELATED APPLICATIONS

This application is a continuation in part of non-provisional application Ser. No. 12/951,052 filed on Nov. 21, 2010.

FIELD OF THE INVENTION

The present invention relates to a process and apparatus for treating fibers and fiber bundles. More specifically, the present invention relates to a process and apparatus for treating raw biomass fibers and fiber bundles that impart properties to the fibers such as improved water holding capacity and crystallinity that are beneficial in a variety of applications such as biofuel manufacturing and soil erosion prevention as well as in products such as plant growth substrates and animal bedding.

BACKGROUND OF THE INVENTION

Biomass materials contain valuable materials that may be used in a variety of applications such as the production of fuels, feeds and chemicals. The release, segregation and collection of these useful materials are accomplished in the art using a variety of chemical, mechanical and enzymatic processes. Of primary benefit is the release of fermentable sugars such as hexose and pentose that can then be used in the production of biofuels such as ethanol. For these processes to be effective, it is desirable to modify the biomass mechanically and chemically.

Prior art references disclose methods for treating fibers with ammonia. U.S. Pat. No. 4,644,060 discloses a method for increasing the bioavailability of polysaccharide components of ligno-cellulosic materials by treatment with ammonia in a supercritical or near-supercritical fluid state at temperatures ranging from 100 degrees C. to 200 degrees C. and pressures ranging from 6.9 MPa to 35 MPa. U.S. Pat. Nos. 5,171,592 and 5,473,061 and US Pre-Grant Publication number 20080008783 describe methods for exploding biomass by rapidly reducing the pressure at which the biomass is treated, thereby exposing the value components in biomass to swelling agents such as ammonia and amines. These processes require high pressure vessels and are difficult and cumbersome to run cost effectively. Also, these processes tend to destroy some the valuable materials in the fibers such as lignin and hemicelluloses.

SUMMARY OF THE PRESENT INVENTION

Fiber treatments are often conducted in liquid dispersion form wherein the liquid contains the appropriate treating agent and the dispersion is heated to a desired temperature level. This method of treatment is typically inefficient and expensive as the unused treating agents must be recovered from the spent liquid for reuse. In the process of the present invention, fibers are continuously treated in the gas phase in which only the needed amount of treating agent is metered into the treatment chamber. In this manner, very little of the treating agent needs to be wasted or needs to be recovered from the process waste stream.

The process of the present invention comprises a process of treating fibers by continually exposing the surfaces of fibers to treatment agents in a gas phase under superheated steam pressure while separating out components such as lignin and hemicelluloses from the fibers that have value in other applications such as soil erosion control and as components in high molecular weight biofuels. The valuable cellulose fibers may be contained in fiber bundles that are byproducts of harvest or sawmill processes of wood or biomass. Separating the fiber bundles is an important step in order to make the fibers accessible to the treatment agents. This is accomplished in the present invention by applying mechanical maceration action to the fibers in such a manner as to expose the fibers to the softening effect of the superheated steam and treatment agents in the gas phase. One such treatment agent is ethylenediamine that is disclosed as an aid in the removal of lignin in U.S. Pat. No. 5,641,385. The lignin acts as glue in the cellulose fiber matrix and therefore reduces the accessibility of reactants that may be used to impart beneficial physical characteristics to the cellulose fibers or to extract valuable chemicals from cellulose and biomass fibers. Sources for biomass fibers include but not limited to: cotton, mulch, switch grass, burr plants, wheat, sorghum, hey, Sudan grass, paper waste, municipal sewer solids, manure solids, sugar cane, cassava, corn and wheat and other cereals straw. The combination of these process steps may be carried out simultaneously at a relatively low pressure of about 2 Kilopascal gauge.

Maceration of fibers in the context of the present invention refers to applying mechanical action to fibers and fiber bundles such as grinding or refining while the fibers are exposed to any or all of the following: liquids, vapors, heat and chemicals. Defiberizing refers to mechanical action applied to fiber bundles with the intent of separating the bundles into smaller bundles and individual fibers, typically under ambient or close to ambient conditions and without chemical aids. Defiberizing is more likely than maceration to result in reducing the length of the fibers.

It is the object of the present invention to provide a process for transforming biomass fibers into materials useable in the production of biofuels. It is also the object of the present invention to provide processes for transforming biomass fibers into materials useable in soil erosion applications and into materials useable as animal feed, animal bedding, and fertilizers. It is further the object of the present invention to provide treated fibers having improved water holding capacity. It is yet another object of the present invention to provide fibers that have a high degree of crystallinity that makes the sugar components of the fibers accessible to enzymatic treatment.

In one aspect of the present invention, a process for treating fibers containing cellulose, lignin and hemicelluloses wherein the fibers typically are aggregated into bundles comprises: softening the fibers; swelling the fibers; macerating the fibers; and removing at least a portion of the lignin and hemicelluloses from the fibers.

In another aspect of the present invention a process for treating fibers comprises: providing fibers and fiber bundles having a moisture level in the range of between about 2 percent and about 10 percent; providing a treatment apparatus comprising a treatment chamber having a feed zone and an exit zone, the treatment chamber being adapted for pressurization; feeding fibers and fiber bundles into the feed zone of a treatment apparatus and moving the fibers and fiber bundles from the feed zone toward the exit zone; pre-treating the fibers and fiber bundles via a feed port disposed in the feed zone of the treatment chamber; macerating the fibers and fiber bundles; feeding a gaseous mixture containing steam, ammonia and ethylenediamine into the treatment chamber via at least one feed port disposed immediately downstream from the feed zone at a temperature of between about 140 degrees C. and about 180 degrees C. and a pressure of about 2 kilopascals gauge; and collecting the fibers at the exit zone of the treatment apparatus, the fibers exiting from the treatment chamber having a moisture level in the range of between about 40 percent and about 60 percent.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front side cross sectional view of an apparatus for treating fibers according to an embodiment of the present invention;

FIG. 2 is a side cross sectional view of the apparatus for treating fibers according to an embodiment of the present invention; and

FIG. 3 is a front side view of an apparatus for treating fibers according to an embodiment of the present invention showing chemical treatment feed points.

FIG. 4 is a front side cross sectional view of an apparatus for treating fibers according to another embodiment of the present invention;

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention.

The present invention relates to a process for producing fibers useful in a variety of applications from fibers that originate from brush, trees and plants that undergo processes which create residuals. Frequently, these residuals come in the form of fiber bundles that, at present, are mostly disposed of as waste. The sources include, wood chips and saw dust that originate from saw mill residuals, mulch and biomass residuals from processing cotton, animal manure fibers, switch grass, burr plants, wheat, barley, oats, rye, triticale, sorghum, hey and Sudan grass the fiber bundles contain cellulosic components that may be useful as additives in animal feed and potting soil, soil erosion prevention and production of biofuels. However, the fibers must first be released from the bundles and rendered in a form amenable to further treatments and transformations. The process of the present invention accomplishes the release of the useful cellulosic components in the fibers by subjecting the fibers and the fiber bundles to four steps that take place substantially simultaneously and continuously: softening, swelling, macerating, and removing at least a portion of materials that are valuable in various other applications such as lignin and hemicelluloses.

The treatment apparatus constitutes a modified pin mixer having a configuration such as that disclosed in U.S. Pat. No. 4,334,788. The apparatus comprises a long cylindrical chamber configured to operate under relatively low pressure. A plurality of pins is disposed on and attached to a central shaft configured longitudinally along the chamber and adapted to rotate radially. The pins may be disposed perpendicularly in relation to the shaft and may be arranged in a plurality of rows offset radially from one to another. The chamber comprises inner cylindrical walls that are modified to contain a plurality of channels disposed longitudinally along the inner surface of the chamber. The channels may range from about 0.2 inches to about 0.5 inches in width and from about 0.2 inches to about 0.5 inches in depth, and their clearance from the unattached end of the pins may range from about 0.1 inches to about 0.3 inches. Fibers and fiber bundles are fed through a feed opening most typically using a screw feeder. As the fibers move through the chamber and toward the exit opening, fiber bundles accumulate inside the channels and separate into smaller bundles from the macerating, rubbing and crushing action of the pins as the shaft rotates; all the while the fibers and fiber bundles continue a forward movement from the feed opening to the exit opening. The pin to fiber action also results in opening the fiber walls as well as fiber length reduction which may be undesirable. The treatment apparatus may operate continuously or in a batch mode and vary in length from about 5 feet to over 20 feet.

A mixture of steam, gaseous ammonia and gaseous amine that may contain urea and ethylenediamine is fed through one or more feed ports in the chamber. In an embodiment of the present invention, superheated steam at a temperature in the range of about 140-180° C. and a pressure of about 2 Kilopascals gauge is used. The steam softens the fiber bundles, which facilitates the macerating action of the pins to separate the fibers while reducing the likelihood of fiber length reduction. The exposure of the fibers to gaseous ammonia results in the swelling of the fibers consistent with the disclosure in U.S. Pat. No. 5,473,061. The swelling of the fibers further facilitates fiber maceration without excessive fiber damage. As the maceration of the fibers proceeds, lignin and hemi-cellulose fragments are separated from the cellulosic components of the fibers. The separated lignin and hemi-cellulose materials are valuable components that can be utilized in the production of biofuels and in soil erosion protection applications. As lignin and hemicelluloses are removed, the crystalline components of the fibers are exposed to chemical and enzymatic treatment. The removal of these materials is aided in the context of the present invention by the use of ethylenediamine consistent with the disclosure in U.S. Pat. No. 5,641,385.

It will be appreciated by those skilled in the art that the continuous feeding of the fiber bundles and the continuous feeding of the gaseous mixture containing steam, ammonia gas and ethylenediamine allow carrying out the process steps of: softening the fibers, swelling the fibers, macerating the fibers and removing at least a portion of the lignin and hemicelluloses to occur substantially simultaneously in the treatment apparatus and to proceed in a substantially continuous manner. It will also appreciated by those skilled in the art that in a continuous operation, feeding the gaseous mixture may be optimized for the feeding rate that matches those of the fibers in a way that the ammonia and ethylenediamine produce the best treatment results, allow recycling spent chemicals if needed and produce minimum waste for disposal. The mechanical treatment variables have a major effect on the continuous treatment process of the fibers. Specifically, it was found experimentally that the best results were achieved for pin rotation speeds in a range from about 800 to about 2000 rpm. For the purposes of the present invention, the pins may be arranged in six to eight rows around the shaft, with each row having 2-5 pins per foot of shaft length.

In an embodiment of the present invention, a gaseous mixture of ammonia, superheated steam and ethylenediamine is produced by heating an aqueous solution containing an ammonium based compound and ethylenediamine to a temperature of about 140-180° C. The ammonium based compound may be anhydrous ammonia or urea. The anhydrous ammonia is easily vaporized, while urea dissociates into ammonia NH₃ and iso-cyanic acid HNCO at about 140° C. The ethylenediamine also exists in the gas phase in this temperature range, as its boiling point is about 116° C. The steam in this temperature range of about 140-180° C. and pressure of about 2 Kilo Pascal gauge is in the superheated range. The application rate of ethylenediamine may be in the range of about 2% to about 15% on dry fibers. A preferred application rate for urea or anhydrous ammonia may be about twice that of ethylenediamine, i.e., in the range of about 4% to about 30% on dry fibers. Optionally, ethanol is added to the gaseous mixture at about 10% by volume of the mixture.

It is important that the fibers fed into the treatment apparatus have low moisture. Ideally, the fibers are air dried to a moisture range in between about 2 percent and about 10 percent. Normally, the fibers pick up moisture in the course of the treatment from steam condensation. Ideally the moisture of the treated fibers is in the range of about 40% and does not exceed 60% in order to avoid plugging the inner wall channels. An excessive increase in fiber moisture pickup would require a significant increase in chemical usage. Similarly, a higher application rate is typically needed if the fiber mix contains relatively large bundles.

A defiberizing step may be required prior to treatment if the bundles are larger than about 1 inch or the fibers are longer than about 1 inch. Defiberizing may be accomplished by methods known in the art such as grinding, hammer-milling and refining.

In the preferred embodiment of the present invention, the fibers are pretreated with an alkaline solution, such as sodium or potassium hydroxide applied in the feed zone as a fine atomizing spray on the fibers and fiber bundles as they are introduced in the feed zone. The concentration of the alkali is preferably in the range of about 1%-4% percent and the application rate of the alkali is in the range of about 0.01% to about 0.3% by weight of the oven dry fiber.

In another embodiment of the present invention, a strong acid such as sulfuric acid, nitric acid and hydrochloric acid may be used as an alternative to the alkaline treatment. The preferred concentration of the acid is about 1% percent and the application rate is in the range of about 0.01% to about 0.1% by weight of the oven dry fiber. The acid may be introduced in the feed zone as a fine atomizing spray on the fibers and fiber bundles as they are introduced in the feed zone.

The gaseous mixture containing ethylenediamine, steam and urea or anhydrous ammonia is preferably introduced into the treatment chamber after the pretreatment through one or more ports disposed through the length of the treatment apparatus. A manifold may distribute the gaseous feed into at least three feed ports with the first port immediately following the feed zone port where the pretreatment spray is introduced.

The fibers exiting from the treatment apparatus may be further washed to remove any residual lignin and hemi-cellulose fragments then dried. The treated fibers have significantly improved water holding capacity compared to untreated fibers, which make them suitable for soil erosion applications, soil potting, seed bedding, animal feed, and fertilizer with slow release. The crystallinity of the fibers is also significantly improved which makes the sugar components, e.g., glucan, more accessible to enzymatic treatment. For biofuel production, the treated fibers are further reacted with sacharifier enzyme and fermenting yeast.

FIGS. 1 and 2 illustrate the apparatus 10 for treating fibers showing the pins 11, the shaft 14 adapted for radial rotation, chamber walls 19, channels 17 and a base 15. In an embodiment of the present invention the pins 11 have a straight shape. In an alternate embodiment, at least some of the pins have a helical shape 11A as shown in FIG. 4. The helical shape of the pins 11A helps move the fibers from the feed zone to the exit zone. In yet another alternate embodiment, the pins may also have a triangular shaped extension at the unattached top end 11B as shown in FIG. 4. This extension also helps move the fibers from the feed zone to the exit zone.

The apparatus illustrated in FIG. 1 represents a batch system equipped with a raw material feed (not shown) configured to feed under pressure. FIG. 3 shows the batch apparatus in a closed position with a feed zone at 22 and an exit zone at 21. In the preferred embodiment of the present invention, the feed port 27 for the pretreatment spray is disposed in the feed zone 22 of the apparatus and at least three feed ports 25 for the ammonium based compound and ethylenediamine follow the feed port and are disposed throughout the length of the treatment chamber up to the exit zone 21. The optimal results are obtained if the first feed port 25 for the ammonium based compound and ethylenediamine immediately follows the feed port 27 for the pretreatment spray. The feed ports may be supplied through a manifold 28 as shown in FIG. 3.

It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention.

EXAMPLES

The following tables provide ethanol conversion efficiencies and water holding capacity measurements for treated fibers resulting from two fiber treatment processes. The fibers originated from several biomass sources.

Untreated fibers were produced by macerating the fibers in a pin mixer in the presence of steam at about 150 degrees C. and a pressure of about 2 Kilo Pascal gauge for about 10 minutes but without the introduction of chemicals into the treatment vessel.

Process 1 comprised of spraying the fibers bundles with a 4% Calcium Oxide by weight of oven dried fibers, macerating the fibers in a pin mixer in the presence of steam at about 150 degrees C., and ammonia originating from heating a solution containing about 5% urea by weight of the dry fibers. The pressure in the treatment vessel was 2 Kilo Pascal gauge. The process was carried out for 5 minutes of dwell time and for 10 minutes of dwell time in the treatment vessel.

The treated fibers were collected from the treatment vessel and converted to Ethanol according to National Renewal Energy Laboratory (NREL) Laboratory procedure LAP-008. Simultaneous saccharification and fermentation experiments were conducted. Each SSF flask was loaded with 3% (w/w) glucan, 1% (w/v) yeast extract, 2% (w/v) peptone, 0.05 M citrate buffer (pH 4.8), the appropriate amount of cellulose enzyme (Spezyme CP, provided by NREL) to achieve 10 FPU/g glucan, the appropriate amount of Saccharomyces cerevisiae D₅A (provided by NREL). The flasks were equipped with water traps to maintain anaerobic conditions and were incubated at 37 C with gentle rotation for a period of 168 hours. The amount of ethanol generated in this process provided a % yield relative to the weight of the dry treated fibers.

The water holding capacity was determined by the steps of 1) drying the treated fibers, 2) saturating the fibers with excess water for one minute, 3) draining the excess water in a strainer until the gravitational water drainage stops and 4) weighing the fibers after the excess water drainage. The water holding capacity was then determined as the weight ratio of the water pick-up to the dry fibers.

The crystallinity of the fibers was measured using a multi-wire x-ray diffraction detector by the Bruker-AXS Corporation in Madison, Wis. The results are shown in the tables below:

Test Results for the Untreated Fibers

Untreated Crystallinity Water Holding fiber ethanol Fiber/Source (%) Capacity, g/g yield (%) Sudan grass 0 2.7 35 Johnson grass 0 33 Hay grass 0 3.0 33 Wheat straw 0 2.9 36 Sorghum 0 3.7 30 Switch grass 0 2.6 32 Sugar cane 0 34 baggase Cotton trash 0 2.5 30 Rice straw 0 36 Wood fibers 0 1.7 36

Five Minute Pre-Treatment

Crystallinity Water holding Ethanol Fiber/Source (%) capacity (g/g) yield (%) Sudan grass 20 4.2 82 Johnson grass 20 4.3 80 Hay grass 23 3.8 82 Wheat straw 25 4.5 83 Sorghum 22 5.5 83 Switch grass 26 6.7 80 Sugar cane 23 5.8 85 baggase Cotton trash 23 5.6 79 Rice straw 20 4.6 85 Wood fibers 28 5.6 85

Ten Minute Pre-Treatment

Crystallinity Water holding Ethanol Fiber/Source (%) capacity (g/g) yield (%) Sudan grass 42 7.2 91 Johnson grass 45 7.2 90 Hay grass 45 6.6 89 Wheat straw 47 6.4 91 Sorghum 43 8.1 90 Switch grass 45 9.4 93 Sugar cane 40 7.7 93 baggase Cotton trash 40 7.2 87 Rice straw 45 8.5 92 Wood fibers 45 9.1 92

In Process 2, the fibers were macerated in a pin mixer at 1500 rpm in the presence of steam at about 150 degrees C., a pressure of about 1.7-2.0 Kilo Pascal gauge, ammonia originating from heating a solution containing from 10% urea and 5% ethylenediamine to about 150 degrees C. The process was carried out for 5 minutes of dwell time and for 10 minutes of dwell time.

The treated fibers were collected from the treatment vessel and converted to Ethanol according to National Renewal Energy Laboratory (NREL) Laboratory procedure LAP-008. Simultaneous saccharification and fermentation experiments were conducted. Each SSF flask was loaded with 3% (w/w) glucan, 1% (w/v) yeast extract, 2% (w/v) peptone, 0.05 M citrate buffer (pH 4.8), the appropriate amount of cellulose enzyme (Spezyme CP, provided by NREL) to achieve 10 FPU/g glucan, the appropriate amount of Saccharomyces cerevisiae D₅A (provided by NREL). The flasks were equipped with water traps to maintain anaerobic conditions and were incubated at 37 C with gentle rotation for a period of 168 hours. The crystallinity of the fibers was measured using a multi-wire x-ray diffraction detector by the Bruker-AXS Corporation in Madison, Wis. The results are shown below:

Five Minute Pre-Treatment

Crystallinity Water holding Ethanol Fiber/Source (%) capacity (g/g) yield (%) Sudan grass 38 4.8 85 Johnson grass 38 4.9 83 Hay grass 31 4.1 84 Wheat straw 38 4.9 85 Sorghum 40 5.8 85 Switch grass 40 6.9 82 Sugar cane 44 6.2 87 baggase Cotton trash 38 5.9 82 Rice straw 41 6.2 87 Wood fibers 43 6.1 87

Ten Minute Pre-Treatment

Crystallinity Water holding Ethanol Fiber/Source (%) capacity (g/g) yield (%) Sudan grass 47 7.8 92 Johnson grass 49 7.7 93 Hay grass 49 7.1 91 Wheat straw 50 6.9 93 Sorghum 48 8.8 93 Switch grass 51 9.7 95 Sugar cane 46 8.1 95 baggase Cotton trash 45 7.9 91 Rice straw 50 8.8 95 Wood fibers 50 9.3 95

The crystallinity of the untreated fibers was=0.0, i.e., the untreated fibers were completely amorphous. The enzymatic conversion of the untreated fibers to ethanol ranged from a yield of 30% to 36%. Crystallinity levels of around 50% and enzymatic conversion of ethanol in the 91% to 95% range were achieved with Process 2. Water holding capacity levels in the 7 g/g to around 10 g/g were achieved with this process. A high water holding capacity is a beneficial attribute in soil erosion applications. As can be seen, the process provides significant improvements in fiber crystallinity and water holding capacity. 

1. A process for treating fibers and fiber bundles containing a cellulose fraction, a lignin fraction and a hemicellulose fraction, said process comprising the steps of: softening the fibers; swelling the fibers; macerating the fibers; and removing at least a portion of the lignin fraction and hemicellulose fraction from the fibers;
 2. The process of claim 1 wherein the process steps are carried out substantially simultaneously.
 3. The process of claim 1 wherein the process steps are carried out substantially continuously.
 4. The process of claim 1, wherein an apparatus for carrying out the process for treating fibers comprises: a chamber having a longitudinal central axis, a cylindrical enclosure, a feed zone and an exit zone, an interior portion having an interior surface and an exterior portion, said feed zone being adapted for communication with a fiber feeding device; a shaft disposed along the longitudinal central axis of said chamber, said shaft being adopted for rotation around said axis; a plurality of pins affixed to said central axis, said pins protruding from the central axis, said pins being substantially perpendicular in relation to the central axis; and a plurality of channels disposed in an inner wall surface of the cylindrical enclosure, said each channel having a predetermined width, a predetermined depth and a predetermined clearance from the pins.
 5. The process of claim 4, wherein at least one of the pins has an upright shape.
 6. The process of claim 4 wherein at least one of the pins has a helical shape.
 7. The process of claim 4 wherein an upper portion of at least one pin comprises a triangular extension.
 8. The process of claim 1 wherein removing at least a portion of the lignin fraction and hemicellulose fraction from the fibers comprises treating the fibers with a mixture of a gaseous amine and superheated steam in a gas phase.
 9. The process of claim 1 wherein softening the fiber bundles comprises subjecting the fiber bundles to superheated steam.
 10. The process of claim 1 wherein swelling the fibers comprises treating the fibers with a mixture of gaseous ammonia and superheated steam in a gas phase.
 11. The process of claim 10, wherein the gaseous ammonia is produced by heating anhydrous ammonia to an anhydrous ammonia boiling point.
 12. The process of claim 10, wherein the gaseous ammonia is produced by heating urea to a urea decomposition temperature.
 13. The process of claim 8, wherein the amine comprises ethylenediamine.
 14. The process of claim 13, wherein a gaseous ethylenediamine is produced by heating a water solution of ethylenediamine to a boiling point of said ethylenediamine, said heating resulting in a mixture of ethylenediamine gas and superheated steam.
 15. A process for treating fibers comprising: providing fibers and fiber bundles having a moisture level in the range of between about 2 percent and about 10 percent; providing a treatment apparatus comprising a treatment chamber having a feed zone and an exit zone, said treatment chamber being adapted for pressurization; feeding fibers and fiber bundles into the feed zone of a treatment apparatus and moving said fibers and fiber bundles from the feed zone toward the exit zone; pre-treating the fibers and fiber bundles via a feed port disposed in the feed zone of the treatment chamber; macerating the fibers and fiber bundles; feeding a gaseous mixture containing steam, ammonia and ethylenediamine into the treatment chamber via at least one feed port disposed immediately downstream from the feed zone at a temperature of between about 140 degrees C. and about 180 degrees C. and a pressure of about 2 kilopascals gauge; and collecting the fibers at the exit zone of said treatment apparatus, said fibers exiting from the treatment chamber having a moisture level in the range of between about 40 percent and about 60 percent.
 16. The process of claim 15 wherein the treatment apparatus comprises: a chamber having a longitudinal central axis, a cylindrical enclosure, an interior portion having an interior surface and an exterior portion, said feed zone being adapted for communication with a fiber feeding device, said chamber being adapted for utilization under pressure; a shaft disposed along the longitudinal central axis of said chamber, said shaft being adopted for rotation around said axis; a plurality of pins affixed to said central axis, said pins protruding from the central axis, said pins being substantially perpendicular in relation to the central axis; and a plurality of channels disposed in an inner wall surface of the cylindrical enclosure having a predetermined width, a predetermined depth and a predetermined clearance from the pins.
 17. The process of claim 16, wherein the clearance between the channels and an upper portion of the pins ranges from about 0.1 inches to about 0.3 inches.
 18. The process of claim 16, wherein the depth and the width of said groves range from about 0.2 inches to about 0.5 inches.
 19. The process of claim 15, wherein a method for producing the gaseous mixture containing steam, ammonia and ethylenediamine comprises heating an aqueous solution containing an ammonium base compound and ethylenediamine to a temperature between 140° C. and 180° C.
 20. The process of claim 15, further comprising washing the fibers collected at the exit of the treatment apparatus, and drying the fibers.
 21. The process of claim 16, wherein macerating the fibers comprises rotating the shaft at a speed of between 800 and 2000 revolutions per minute.
 22. The process of claim 15, further comprising defiberizing the fiber bundles prior to feeding the fiber bundles into the treatment chamber.
 23. The process of claim 15, wherein the gaseous mixture further comprises about 10% ethanol by volume.
 24. The process of claim 19, wherein the ammonium base compound is selected from the group consisting of urea and ammonium anhydride, and a feed rate of said ammonium base compound ranges from about 4 percent to about 30 percent by weight of the dry fibers.
 25. The process of claim 19, wherein a feed rate of the ethylenediamine ranges from about 2 percent to about 15 percent by weight of the dry fibers.
 26. The process of claim 15 wherein pre-treating the fibers and fiber bundles comprises spraying droplets of an alkaline solution at an application rate ranging from about 0.01% to about 0.3% by weight of the oven dry fiber, wherein an alkaline component of the alkaline solution is selected from the group consisting of sodium hydroxide, calcium hydroxide and potassium hydroxide.
 27. The process of claim 15 wherein pre-treating the fibers and fiber bundles comprises spraying droplets of an acid solution at an application rate ranging from about 0.01% to about 0.1% by weight of the oven dry fiber, said acid being selected from the group consisting of sulfuric acid, nitric acid and hydrochloric acid. 